Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932205AbWEGRhP (ORCPT ); Sun, 7 May 2006 13:37:15 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932207AbWEGRhP (ORCPT ); Sun, 7 May 2006 13:37:15 -0400 Received: from mail.gmx.net ([213.165.64.20]:60902 "HELO mail.gmx.net") by vger.kernel.org with SMTP id S932205AbWEGRhN (ORCPT ); Sun, 7 May 2006 13:37:13 -0400 X-Authenticated: #14349625 Subject: Re: sched_clock() uses are broken From: Mike Galbraith To: Russell King Cc: Nick Piggin , Andi Kleen , Christopher Friesen , linux-kernel@vger.kernel.org In-Reply-To: <20060507124307.GA20443@flint.arm.linux.org.uk> References: <20060502132953.GA30146@flint.arm.linux.org.uk> <44578EB9.8050402@nortel.com> <200605021859.18948.ak@suse.de> <445791D3.9060306@yahoo.com.au> <1146640155.7526.27.camel@homer> <445DE925.9010006@yahoo.com.au> <20060507124307.GA20443@flint.arm.linux.org.uk> Content-Type: text/plain Date: Sun, 07 May 2006 19:37:13 +0200 Message-Id: <1147023433.13315.22.camel@homer> Mime-Version: 1.0 X-Mailer: Evolution 2.4.0 Content-Transfer-Encoding: 7bit X-Y-GMX-Trusted: 0 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1221 Lines: 30 On Sun, 2006-05-07 at 13:43 +0100, Russell King wrote: > On Sun, May 07, 2006 at 10:33:41PM +1000, Nick Piggin wrote: > > Mike Galbraith wrote: > > >On Wed, 2006-05-03 at 03:07 +1000, Nick Piggin wrote: > > > > > >>Other problem is that some people didn't RTFM and have started trying to > > >>use it for precise accounting :( > > > > > > > > >Are you talking about me perchance? I don't really care about precision > > >_that_ much, though I certainly do want to tighten timeslice accounting. > > > > No, sched_clock is fine to be used in CPU scheduling choices, which are > > heuristic anyway (although strictly speaking, even using it for timeslicing > > within a single CPU could cause slight unfairness). > > Except maybe if it rolls over every 178 seconds, which is my original > point. Maybe someone could comment on my initial patch sent 5 days > ago? Simply ignore the wrap... unless you have a scenario where the wrap event itself is significant event. -Mike - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/